While installing Mageia 1 on a Dell Inspiron E1405 laptop (also known as the Inspiron 640m), I closed the lid which turned the screen off. Opening it up later, the screen did not turn back on. I was able to turn it back on manually by executing a command at the console, as follows:
Ctrl-Alt-F2 (switch to console)
vbetool dpms on
From lspcidrake:
unknown : Intel Corporation|Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller [DISPLAY_OTHER] (rev: 03)
Card:Intel 810 and later: Intel Corporation|Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller [DISPLAY_VGA] (rev: 03)
unknown : Intel Corporation|Mobile 945GM/PM/GMS, 943/940GML and 945GT Express Memory Controller Hub [BRIDGE_HOST] (rev: 03)
Note that in the installed system itself, the blanking/unblanking functionality works fine.

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It's worse now in Cauldron. Not only is it not fixed (not that there was any reason to believe that it might have been), vbetool doesn't work in the installer anymore. It gives a message (assuming you run it before the screen is blanked so that you can see it) failed to initialize Linux Real Mode Interface. So now if the screen gets blanked, there's no way to recover from it.

My first guess would have been maybe do we lack a kernel module?
But, from reading the code, the "Failed to initialise LRMI (Linux Real-Mode Interface)" error messages cames when it fails to open or process /dev/mem
Is there any other messages before/after?
All errors pathes are using perror() to report issues...
The following bug reports points to permission issues due to dracut
https://bugzilla.redhat.com/show_bug.cgi?id=710711
Colin, WDYT about lessening perms for installer?
If that doesn't fix it, another hint the libx86 patch that stops some mmap() of page zero is causing havoc?
https://bugzilla.redhat.com/show_bug.cgi?id=518351
But I'm guessing for noexec mounting of /dev/

(In reply to Thierry Vignaud from comment #13)
> My first guess would have been maybe do we lack a kernel module?
>
> But, from reading the code, the "Failed to initialise LRMI (Linux Real-Mode
> Interface)" error messages cames when it fails to open or process /dev/mem
>
> Is there any other messages before/after?
> All errors pathes are using perror() to report issues...
>
> The following bug reports points to permission issues due to dracut
> https://bugzilla.redhat.com/show_bug.cgi?id=710711
>
> Colin, WDYT about lessening perms for installer?
This is a really old bug and references a really old dracut commit that we've not carried for some time.
Do we mount /dev in the installer ourselves these days? (I don't see it with a git grep).
Not 100% sure what you're asking me to do with regards to permissions...
> If that doesn't fix it, another hint the libx86 patch that stops some mmap()
> of page zero is causing havoc?
> https://bugzilla.redhat.com/show_bug.cgi?id=518351
>
> But I'm guessing for noexec mounting of /dev/
I don't see where /dev/ gets mounted noexec... Dracut code doesn't seem to do it (just grep for devtmpfs, and a systemd system without initramfs doesn't do it. Can you point to some background as to why you think the affected systems have a noexec mounted /dev?

In that case I can only test it in Mageia 4, as that's what's installed on the machine. vbetool works fine from root. If I try to run it from a regular user account, it says open /dev/mem: Permission denied, and gives the LRMI error too.

(In reply to David Walser from comment #20)
> In that case I can only test it in Mageia 4, as that's what's installed on
> the machine. vbetool works fine from root. If I try to run it from a
> regular user account, it says open /dev/mem: Permission denied, and gives
> the LRMI error too.
I don't know the tool, but I would expect it to fail as non-root if it's accessing /dev/mem and it's not setuid or anything special.
Is this tool integrated anywhere in such a way that it's called as a regular user? If so, that's likely a bug. If this is just a local thing that is done locally for a specific h/w hack, then I'd just setup a sudo or policykit rule accordingly and run it via sudo/pkexec or similar.
It's probably possible to use an MGA5 live media (and still recompile it after urpmi the build reqs!) if it needs testing on this h/w on newer builds - assuming you have enough memory to play with :)

No, it's fine that it doesn't work as regular user. Where it's tied in is to ACPI events, so that it is used to blank and turn on the screen when the lid is closed and opened. In an installed Mageia 4 system, this works fine. The original issue for this bug is that in the installer, it only blanks the screen when you close the lid, and fails to turn it back on when you open it. Before mga5 Cauldron, you could at least manually Ctrl-Alt-F2 and then run vbetool to turn it back on, but this problem was made worse when that stopped working too. Both of these issues really need to be fixed.
As far as testing, the best I can do is try running vbetool on a Cauldron machine at work, but that's not a laptop.

Let me first be clear, this is the kind of bug that isn't going to just disappear on its own. It won't be fixed until something is actively done to fix it.
Either there's something in the installer that's triggering the screen to blank without a matching thing to unblank it, or there's something intrinsic in this hardware causing it to blank, and the installer is missing something to disable that or to unblank the screen when the lid is opened.
Just to humor you, I have confirmed that the bug is still present in current Cauldron.